Control system for limiting overload and overrunning of an internal-combustion engine

ABSTRACT

A control system for limiting overload and overrunning of an internal-combustion engine having diaphragm-operated intake sectional area control means from the vacuum of the air intake systems employs a solenoid valve operating when the r.p.m. of the engine or the power thereof exceeds a predetermined limit to terminate operation of the diaphragm.

United States Patent 5111301111111 Nakata Aid-gun, Japm July 9, 1969 Aug. 3, 1971 'l'oyo Kogyo Co., Ltd.

Aki-Gun Hirmhima-Ken, Japan Priority July 11, 1968 Japan Inventor Appl. No. Filed Patented Assignee CONTROL SYSTEM FOR LIMITING OVERLOAD AND OVERRUNNING OF AN INTERNAL- coMBusnoN ENGINE 6 Claims, 5 Drawing ri us. (:1 123/103, 123/97, 123/127 1111.01 F020 11/08, FOZm 13/04, F0211 9/00 Field of Search ..123/103, 97 B, 127

[56] References Cited UNITED STATES PATENTS 2,962,015 11/1960 Serruys et a1. 123/103 3,021,827 2/1962 Brunner 123/103 X 3,249,099 5/1966 Saxby 123/127 X 3,342,463 9/1967 Date et a1. 123/103 X 3,444,848 5/1969 Lawrence 123/127 Primary Examiner-Wendell E. Burns Auorney- Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT: A control system for limiting overload and overrunning 'of an internal-combustion engine having diaphragmoperated intake sectional area control means from the vacuum of the air intake systems emp1oys a solenoid valve operating when the r.p.m. of the engine or the power thereof exceeds a predetennined limit to terminate operation of the diaphragm.

PATENTEDYAUE s an v I 35961642 SHEETIUFZ PATENTED Aus 3197i ENG PWR FIG. 4

ENG SP RPNF" FIG. 5

" ENG SP RPM CONTROL SYSTEM FOR LIMITING OVERLOAD AND OVERRUNNING OF AN INTERNAL-COMBUSTION ENGINE BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a control system for limiting overload and overrunning of an internal-combustion engine, and more particularly to a system which operates by closing an intake sectional area control such as a secondary throttle valve or variable-area venturi of a carburetor at a predetermined limit above engine capacity.

If the engine is operated at an overload or under an overrunning condition above the limit of the engine capacity, it shortens its life and makes additional noise.

SUMMARY OF THE INVENTION This invention, therefore, eliminates this and other drawbacks thus far inherent in the conventional intemal-combustion engine. It provides a control system for limiting overload and overrunning of an internal-combustion engine having a carburetor including intake sectional area control means adapted to open at load condition of the engine by vacuum in the air intake system of the engine. A throttle valve mechanically opens or closes by an accelerator pedal in conventional fashion. When the engine operates to exceed its limit, the engine vacuum is released by introducing atmosphere into the vacuum chamber to which the vacuum in the intake system of the engine is led, and the intake sectional area control means is automatically closed.

Where the engine has a carburetor having primary and secondary barrels, a secondary throttle valve acts as the intake sectional area control means in the secondary barrel which is operated by means of vacuum in the air intake system of the engine.

In another embodiment, an engine has a carburetor with a variable-area venturi as the intake sectional area control means operated by the vacuum in the air intake system of the engine with the throttle valve operated mechanically through the accelerator pedal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a control system embodying the present invention for limiting overload and overrunning of an internal-combustion engine.

FIG. 2 is similar to FIG. 1 but showing a second embodiment of the present invention.

FIG. 3 is a sectional view of a control system for limiting overload and overrunning of an internal-combustion engine having a carburetor of variable-area venturi type, as a third embodiment of the present invention.

FIGS. 4 and 5 are graphical representations of characteristics of the first and second embodiments of the present invention, shown in FIGS. 1 and 2, respectively.

DESCRIPTION OF PREFERRED EMBODIMENTS A first example of a control device for limiting overload and overrunning of an internal-combustion engine is shown in FIG. 1. A carburetor 12 of the constant-area venturi type includes a primary throttle valve 13, operated by an accelerator pedal 11 though a mechanical linkage 14 in a first barrel 15 for a primary venturi 16. A secondary throttle valve 17 lies in a secondary barrel 13 carrying a secondary venturi 19. A vacuum inlet port 20 opens into the primary venturi l6 and another vacuum port 21 opens into the secondary venturi 19 and communicates with the vacuum inlet port 20. Vacuum diaphragm means 22 includes a diaphragm 23, which divides it into two chambers including a vacuum chamber 24 communicating with the vacuum inlet ports 20 and 21 through passage 25. An air chamber 26 communicates with the atmosphere. The diaphragm 23 is mechanically linked to the secondary throttle valve 17 by linkage 27 for opening and closing the throttle valve 17 by the displacement of the diaphragm 23. Solenoid valve means 28 includes a solenoid valve 29 having an opening 30 which communicates with the vacuum chamber 24 of the diaphragm means 22. A valve body 29a selectively closes or opens opening 30. A spring 31 is so disposed as to normally close the opening 30 by urging the valve body 29a closed, for controlling the communication of the vacuum chamber 24 of the diaphragm means 22 with the atmosphere through a port 32. A solenoid coil 33 operates to open the opening 30 when energized, so as to connect the vacuum chamber 24 of the diaphragm means 22 with the atmosphere through port 32. An engine speed detector 34 is coupled to an engine shaft (not shown). A control switch 35 closes to energize the solenoid coil 33 when the engine speed detected by the detector 34 exceeds a predetermined limit. An electric storage source 36 is connected by the switch 35 to the solenoid coil 33.

In operation of the arrangement thus constructed as previously described, when the engine speed exceeds a predetermined limit, the switch 35 closes under control of the detector 34 to cause the energization of the solenoid coil 33 through electric storage source 36. The result is that the valve body 29a opens opening 30. The atmosphere is introduced through port 32 and opening 30 into the vacuum chamber 24 of diaphragm means 22. With atmospheric pressure in vacuum chamber 24 of the diaphragm means 22, the vacuum introduced from the venturis 16 and 19 through the ports 20 and 21 and passage 25 into the vacuum chamber 24 of the diaphragm means 22 is cancelled so that the diaphragm 23 closes the secondary throttle valve 17 disposed in the secondary barrel 18 of the carburetor 12.

The operation will now be described in more detail with reference to FIG. 4.

The broken curve A designates a characteristic where only the primary throttle valve 13 opens while the secondary valve 17 is closed. The curve B shows a characteristic where both the primary and secondary throttle valves 13 and 17 operate normally. When the engine reaches a predetermined speed limit N, the secondary throttle valve 17 is closed by the operation of the detector 34, switch 35, solenoid valve means 28, and diaphragm means 22 as previously mentioned, so that the power of the engine is reduced. It follows that if an overload is applied to the engine at that time, the engine speed decreases and it prevents the overrunning of the engine. When the engine speed again decrease below the predetermined limit N, the secondary throttle valve 17 opens again to accelerate the engine. Here, in order to avoid the fluctuation of the opening and closing operations of the switch 35 near the engine speed N, it is preferable to provide a hysteresis so as to make a difference between that engine speed when the switch 35 opens and that speed when the switch 35 closes. Thus, the engine operation in the hatched area shown in FIG. 4 is restricted.

A second embodiment of the control device for limiting overload and overrunning of an internal-combustion engine is described with respect to FIG. 2. Like numerals designate like parts. A carburetor 12 of the constant-area venturi type includes a primary throttle valve 13, acting in cooperation with the accelerator pedal 11 by mechanical linkage 14, in a primary barrel 15 for a primary venturi 16. A secondary throttle valve 17 is carried in a secondary barrel 18 as is secondary venturi 19. A vacuum inlet port 20 opens into the primary venturi l6 and another vacuum inlet port 21 opens into the secondary venturi l9 and communicates with the vacuum inlet port 20. Vacuum diaphragm means 22 includes a diaphragm 23 dividing it into two chambers; a vacuum chamber 24 which communicates with the vacuum inlet ports 20 and 21 through a passage 25 andan air chamber 26 which communicates with the atmosphere. The diaphragm 23 is mechanically linked to the secondary throttle valve 17 by linkage 27 for opening and closing the throttle valve 17 disposed in the second barrel 18 through displacement of diaphragm 23. Solenoid valve means 28 includes a solenoid valve 29 having an opening 30 which communicates with the vacuum chamber 24 of the diaphragm means 22, a valve body 29a for closing or opening opening 30 and a spring 31 so disposed as to normally close the opening 30 by urging the valve body 29a thereagainst. This controls the communication of the vacuum chamber 24 of the diaphragm means 22 with the atmosphere through port 32 connected with the atmosphere. A solenoid coil 33 is adapted to open the opening 30, when energized, so as to connect the vacuum chamber 24 of the diaphragm means 22 with the atmosphere through port 32. A control switch 37 closes electrical contacts 38 when vacuum at the secondary venturi 19, directed through a port 39 and passage 40, exceeds a predetermined value to energize solenoid coil 33.

In the operation of the arrangement of the control device thus described, when the vacuum at the secondary venturi l9 exceeds a predetermined value or limit, the contacts 38 of the switch 37 close so that the solenoid coil 33 is energized by the electric storage source 36. This results in the solenoid valve opening so that the atmosphere is introduced through port 32 and opening 30 into the vacuum chamber 24 of the diaphragm means 22. When the atmosphere is thus introduced into the vacuum chamber 24 of the diaphragm means 22, the vacuum introduced from the venturis 16 and 19 through the ports and 21 and passages into the vacuum chamber 24 of the diaphragm means 22 is cancelled by the introduction of the atmosphere thereinto so that the diaphragm 23 closes the secondary throttle valve 17 disposed in the secondary barrel 18 of the carburetor 12. The vacuum at the venturi 19 is generally proportional to the engine power so that if the engine power exceeds a predetermined limit P, the secondary throttle valve 17 is closed by the switch 37, solenoid valve means 28, and diaphragm means 22 to cause a decrease in engine power.

As shown in H6. 5, by the second embodiment, engine operation is restricted from the hatched area that is over the engine power limit P.

A third embodiment of the control system for limiting overload and overrunning of an internal-combustion engine is described with reference to FIG. 3. Like parts have like numeral designations. A carburetor 41 of the variable-area venturi type includes a throttle valve 13 acting in cooperation with an accelerator pedal (not shown) by mechanical linkage (not shown). A carburetor body 42 carries a flow control assembly or an intake sectional area control means 43 having a suction piston 44 of known construction, a venturi 45 defined by the bottom wall of the suction piston 44 and bridge portion 42a. A tapered needle 46 is secured-to the bottom wall of the suction piston 44 and is movably inserted into the fuel jet 47. A port 20, formed at the bottom wall of the suction piston 44, communicates with a vacuum chamber 44a behind the suction piston 44. A spring 48 is so disposed as to close the variable venturi by urging the suction piston 44 downwards. A port 49 is formed at the top of the flow control assembly 43. Solenoid valve means 28 includes a solenoid valve 29 having an opening which communicates with port 49 of the flow control assembly 43, a valve body 29a which closes or opens the opening 30. A spring 31 is so disposed as to normally close the opening 30 by urging the valve body 29a closed to control communication between port 49 of the flow control assembly 43 and the atmosphere through port 32. A solenoid coil 33 opens opening 30 of the solenoid valve 29 to the atmosphere through the port 32, using any of the control means for energization of the solenoid coil 33 as shown in FIGS. 1 and 2.

In operation of the arrangement of the control systems of FIG. 3, when the vacuum at the venturi exceeds a predetermined limit when used as the control means for energization of the solenoid coil 33 shown in FIG. 2, the contacts 38 of the switch 37 close so that the solenoid coil 33 is energized by the electric storage source 36 with the result that the solenoid valve 29 is opened. The atmosphere is introduced through port 32 and opening 30 into port 49 of the flow control assembly 43 and further through the inner hole of the suction piston 44 and the port 20 into the intake duct 50 with the result that the variable-area venturi closes by the tension of the spring 48 to cause a decrease in engine power.

i l F intake sectional area control means operated through diaphragm means by the vacuum in the air intake system of the engine, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a vacuum chamber carrying said diaphragm means, said solenoid valve having an opening which communicates with the vacuum chamber and having a valve body closing'and opening said opening, and means for energizing said solenoid coil to open said opening for communicating said vacuum chamber to the atmosphere when the speed or power exceeds a predetermined limit, means incorporating said solenoid coil within a circuit including a switch which closes and opens said circuit, said switch being operatively coupled to the air intake system of the engine.

2. A control system for limiting overload and overrunning of an internal-combustion engine'having a carburetor with primary and secondary barrels, each having a constant area venturi, a primary throttle valve mechanically coupled to an accelerator and a secondary throttle valve operatively coupled to a diaphragm means, means for coupling the vacuum air in take system to a vacuum chamber of the diaphragm means, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit including an electrical source, said solenoid coil and a switch which closes and opens said circuit, a detector for detecting the speed of the engine, said solenoid valve having an opening communicating with said vacuum chamber of said diaphragm means, a port communicating with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to normally close said opening, means operatively coupling said engine speed detector to said switch for closing said switch to energize said solenoid coil and draw said valve body against said spring when the speed of the engine exceeds a predetermined limit whereby; said vacuum chamber of said diaphragm means is connected to the atmosphere through said opening and said port to close said secondary throttle valve at that engine operation.

3. A control system for limiting overload and overrunning of an internal-combustion engine having a carburetor including primary and secondary barrels, each have a constant area venturi, a primary throttle valve for the primary barrel mechanically cooperated with an accelerator, and a secondary throttle valve for said secondary barrel operated through diaphragm means by directing the vacuum of the air intake system into the vacuum chamber of the diaphragm means, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit including an electrical source, said solenoid coil and a switch'which is operatively coupled to said secondary barrel to close and open said circuit in response to the vacuum of the engine, said solenoid valve having an opening which communicates with said vacuum chamber of said diaphragm means, a port communicating with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to closed position whereby: said switch closes to energize said solenoid coil and draw said valve body against said spring when the vacuum of said second barrel exceeds a predetermined limit under heavy load engine operating conditions with operation of the diaphragm means shut ofi by communicating the vacuum chamber thereof with the atmosphere through the opening and the port with the secondary throttle valve closed at that engine operation.

4. A control system for limiting overload and overrunning of an internal-combustion engine having a variable-area venturi type carburetor including a barrel, a throttle valve in the barrel mechanically coupled to an accelerator and a flow control assembly having a suction piston which defines a variable-area venturi between it and a bridge portion of a carburetor body, a first spring disposed to close the variable-area venturi by urging the suction piston and a port opening into a vacuum chamber behind the suction piston to operate the suction piston against the spring by the vacuum of the air intake system, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit having an electrical source, said solenoid coil and a switch which closes and opens said circuit, said solenoid valve having an opening communicating with said vacuum chamber of said flow control assembly, a second port communicating with the atmosphere, a valve body closing and opening said opening and a second spring urging said valve body into normally closed position, said switch closing to energize said solenoid coil and draw said valve body against said second spring when the engine speed orpower exceeds a predetermined limit whereby the vacuum within the vacuum chamber behind said suction piston is cancelled by communicating said vacuum chamber with the atmosphere through said opening and the second port to close said suction piston at that engine operation.

5. A control system for limiting overload and overrunning of an internal-combustion engine having a carburetor with primary and secondary barrels, each having a constant air venturi, a primary throttle valve mechanically coupled to an accelerator, a vacuum chamber including diaphragm means and means for operatively coupling the vacuum intake system to said vacuum chamber and a secondary throttle valve to said diaphragm means, said control system comprising:

solenoid valve means including a solenoid valve and a solenoid coil,

a circuit including an electrical source, said solenoid coil and a switch which closes and opens said circuit, said solenoid valve having an opening communicating with said vacuum chambervof said diaphragm means, a port communicating with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to normally closed position, and means responsive to a predetermined engine-operating state for closing said switch to energize said solenoid coil and draw said valve body against said spring, whereby; said vacuum chamber of said diaphragm means is con- -nected to the atmosphere through said opening and said port to close said secondary throttle valve at said predetermined engine operation state. I .t 6 ."A control system for limiting overload androverrunning of an intemal-combustion engine having a carburetor including intake sectional area control means operated by the vacuum in the air intake system of the engine within a vacuum chamber of a vacuum-operated means, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit including an electrical source, said solenoid coil and a switchwhich closes and opens said circuit, said solenoid valve having an opening communicating said vacuum chamber of said vacuum-operated means with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to normally close said opening, said switch closed to energize said solenoid coil and draw said valve body against said spring when the engine speed or power exceedsfa predetennined limit whereby said vacuum chamber is connected to the atmosphere through said opening to close said intake sectional area control means at that engine state. 

1. A control system for limiting overload and overrunning of an internal-combustion engine having a carburetor including intake sectional area control means operated through diaphragm means by the vacuum in the air intake system of the engine, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a vacuum chamber carrying said diaphragm means, said solenoid valve having an opening which communicates with the vacuum chamber and having a valve body closing and opening said opening, and means for energizing said solenoid coil to open said opening for communicating said vacuum chamber to the atmosphere when the speed or power exceeds a predetermined limit, means incorporating said solenoid coil within a circuit including a switch which closes and opens said circuit, said switch being operatively coupled to the air intake system of the engine.
 2. A control system for limiting overload and overrunning of an internal-combustion engine having a carburetor with primary and secondary barrels, each having a constant area venturi, a primary throttle valve mechanically coupled to an accelerator and a secondary throttle valve operatively coupled to a diaphragm means, means for coupling the vacuum air intake system to a vacuum chamber of the diaphragm means, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit including an electrical source, said solenoid coil and a switch which closes and opens said circuit, a detector for detecting the speed of the engine, said solenoid valve having an opening communicating with said vacuum chamber of said diaphragm means, a port communicating with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to normally close said opening, means operatively coupling said engine speed detector to said switch for closing said switch to energize said solenoid coil and draw said valve body against said spring when the speed of the engine exceeds a predetermined limit whereby; said vacuum chamber of said diaphragm means is connected to the atmosphere through said opening and said port to close said secondary throttle valve at that engine operation.
 3. A control system for limiting overload and overrunning of an internal-combustion engine having a carburetor including primary and secondary barrels, each have a constant area venturi, a primary throttle vAlve for the primary barrel mechanically cooperated with an accelerator, and a secondary throttle valve for said secondary barrel operated through diaphragm means by directing the vacuum of the air intake system into the vacuum chamber of the diaphragm means, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit including an electrical source, said solenoid coil and a switch which is operatively coupled to said secondary barrel to close and open said circuit in response to the vacuum of the engine, said solenoid valve having an opening which communicates with said vacuum chamber of said diaphragm means, a port communicating with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to closed position whereby: said switch closes to energize said solenoid coil and draw said valve body against said spring when the vacuum of said second barrel exceeds a predetermined limit under heavy load engine operating conditions with operation of the diaphragm means shut off by communicating the vacuum chamber thereof with the atmosphere through the opening and the port with the secondary throttle valve closed at that engine operation.
 4. A control system for limiting overload and overrunning of an internal-combustion engine having a variable-area venturi type carburetor including a barrel, a throttle valve in the barrel mechanically coupled to an accelerator and a flow control assembly having a suction piston which defines a variable-area venturi between it and a bridge portion of a carburetor body, a first spring disposed to close the variable-area venturi by urging the suction piston and a port opening into a vacuum chamber behind the suction piston to operate the suction piston against the spring by the vacuum of the air intake system, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit having an electrical source, said solenoid coil and a switch which closes and opens said circuit, said solenoid valve having an opening communicating with said vacuum chamber of said flow control assembly, a second port communicating with the atmosphere, a valve body closing and opening said opening and a second spring urging said valve body into normally closed position, said switch closing to energize said solenoid coil and draw said valve body against said second spring when the engine speed or power exceeds a predetermined limit whereby the vacuum within the vacuum chamber behind said suction piston is cancelled by communicating said vacuum chamber with the atmosphere through said opening and the second port to close said suction piston at that engine operation.
 5. A control system for limiting overload and overrunning of an internal-combustion engine having a carburetor with primary and secondary barrels, each having a constant air venturi, a primary throttle valve mechanically coupled to an accelerator, a vacuum chamber including diaphragm means and means for operatively coupling the vacuum intake system to said vacuum chamber and a secondary throttle valve to said diaphragm means, said control system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit including an electrical source, said solenoid coil and a switch which closes and opens said circuit, said solenoid valve having an opening communicating with said vacuum chamber of said diaphragm means, a port communicating with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to normally closed position, and means responsive to a predetermined engine-operating state for closing said switch to energize said solenoid coil and draw said valve body against said spring, whereby; said vacuum chamber of said diaphragm means is connected to the atmosphere through said opening and said port to close said secondary throttle valve at said predetermined engine operation state.
 6. A control system for limiting overloaD and overrunning of an internal-combustion engine having a carburetor including intake sectional area control means operated by the vacuum in the air intake system of the engine within a vacuum chamber of a vacuum-operated means, said system comprising: solenoid valve means including a solenoid valve and a solenoid coil, a circuit including an electrical source, said solenoid coil and a switch which closes and opens said circuit, said solenoid valve having an opening communicating said vacuum chamber of said vacuum-operated means with the atmosphere, a valve body closing and opening said opening and a spring urging said valve body to normally close said opening, said switch closed to energize said solenoid coil and draw said valve body against said spring when the engine speed or power exceeds a predetermined limit whereby said vacuum chamber is connected to the atmosphere through said opening to close said intake sectional area control means at that engine state. 